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path: root/drivers/net/ethernet/cadence/macb.c
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Diffstat (limited to 'drivers/net/ethernet/cadence/macb.c')
-rw-r--r--drivers/net/ethernet/cadence/macb.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index 89c0cfa9719f..d954a97b0b0b 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -1323,6 +1323,24 @@ dma_error:
 	return 0;
 }
 
+static inline int macb_clear_csum(struct sk_buff *skb)
+{
+	/* no change for packets without checksum offloading */
+	if (skb->ip_summed != CHECKSUM_PARTIAL)
+		return 0;
+
+	/* make sure we can modify the header */
+	if (unlikely(skb_cow_head(skb, 0)))
+		return -1;
+
+	/* initialize checksum field
+	 * This is required - at least for Zynq, which otherwise calculates
+	 * wrong UDP header checksums for UDP packets with UDP data len <=2
+	 */
+	*(__sum16 *)(skb_checksum_start(skb) + skb->csum_offset) = 0;
+	return 0;
+}
+
 static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	u16 queue_index = skb_get_queue_mapping(skb);
@@ -1362,6 +1380,11 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		return NETDEV_TX_BUSY;
 	}
 
+	if (macb_clear_csum(skb)) {
+		dev_kfree_skb_any(skb);
+		return NETDEV_TX_OK;
+	}
+
 	/* Map socket buffer for DMA transfer */
 	if (!macb_tx_map(bp, queue, skb)) {
 		dev_kfree_skb_any(skb);